http://www.hotwired.com/Coin/Spnsrs/Volvo/Safety/finish.html (The Risc Disc Volume 2, 10/1995)
Body Coatings
A Volvo body is engineered "clean" of unnecessary seam enclosures where
moisture could collect. While the car is still on the assembly line, a thin anti-corrosive gel coating is sprayed through specially provided holes directly into closed body sections: roof pillars, doors, rocker panels. The undersides of engine and suspension system components receive a rustproofing oil spray. Even the driveshaft is sprayed with a light oil protective coating.
Factory Undercoating
We factory-prepare our cars with five different kinds of coatings designed to seal and protect the underbody from the moment the car leaves the assembly plant.
Fender Liners
Underneath the fenders, years of driving can build up a corrosive layer of road dirt, salt spray, and oil residue. Plastic fender liners installed in the front wheel wells help guard against corrosion by keeping dirt and moisture away from the underlying steel - and protecting it from flying stones and gravel. Plastic fender liners are also used in the rear wheel wells of the Volvo 960, 940, and 850.
Hot Melt
Before brake lines, drive shaft and other underbody components are installed, a "hot melt" underseal is baked on all exposed areas.
This hot-melt coating is free from solvents, to protect the environment from industrial pollution during the manufacturing process.
Paint
At Volvo, we build cars to retain their value and their beauty for many
years - so our finish must be particularly durable. It requires a 7-step
process of priming, protective coating, oven baking, sanding, sealing, and painting.
Paint Preparation
The best way to make any painted exterior last longer is by carefully
preparing the surface before paint is applied. Volvo's paint preparation process begins even before body assembly, with a zinc welding primer applied to all critical joints. Caulking compounds are then added to seal body joints during assembly. After assembly, the body is thoroughly cleaned and sprayed with a coating to etch the metal for strong paint adhesion.
Primer Bath
After preparation, every car body is submerged in a primer coating solution. The solution is electrostatically charged with 240 volts to assure that the primer bonds to the metal surface in a thick, even coat. Emerging from its bath, the car body is washed clean of excess primer and oven-baked for even tighter bonding.
Resistance to Chipping
To resist chipping and abrasion, a wet-on-wet spray application of special polyester-based paint is applied to the bottom rails, floor, and area behind the rear wheel arch. Several layers of a special anti-chipping polyester paint are also applied to the lower sheet metal, lower doors, and rocker panels. This chip-resistant paint is designed to remain resilient and to bond more strongly to the car body than to itself, so damage from flying stones will be absorbed within the paint layers rather than make paint chip off.
Top Coats
Beneath the finish lies a whole series of unseen steps designed to keep that finish brighter, longer. After special undercoating paints and sealers are applied, a final primer is sprayed on and baked for firm adhesion. The entire surface is wet-sanded smooth. Then the top coat of enamel is applied wet-on-wet to assure a thick, even finish. Metallic finishes contain reflective mica to achieve a handsome metallic appearance; a final clear coat seals in the metallic enamel and brings out the full depth and beauty of the color.
Ventilation
Rocker panels are especially prone to rust; Volvo has a special "slipstream ventilation" system to prevent it. Rainwater that enters the air intake is forced down and out through exhaust holes in the door sills by a stream of air that evaporated moisture and dries the interior of door and rocker panel.
Zinc coated metal
Perhaps the ultimate step in Volvo's fight against corrosion is the nature of the construction material itself. Virtually all Volvo body panels are made of sheet steel galvanized with zinc. This process not only offers extremely effective protection against rust, but also has remarkable self-healing properties. If minor chips or scratches penetrate the paint layers to the sheet steel, zinc coating molecules will migrate from the surrounding surface to fill in and protect the damaged area.
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